67 lines
1.7 KiB
Markdown
67 lines
1.7 KiB
Markdown
# Protocol Overview
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The Commonwealth Online protocol defines the messages sent between Fallout 4 clients and the external server.
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Early versions should stay simple and easy to debug.
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## Early Design
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The first version can use human-readable packets during testing.
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Long-term versions may move to a binary protocol if performance becomes a problem.
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## First Required Messages
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- `welcome`
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- `transform`
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- `worldState`
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- `worldStateHost`
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- `serverWorldState`
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- `disconnect`
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- `ping`
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- `pong`
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## LAN Discovery (UDP)
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Local server discovery uses a separate UDP channel so clients can find
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Commonwealth Online relays on the LAN without scanning every TCP port.
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- **Discovery port:** `7778` (UDP)
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- **Game port:** `7777` (TCP) by default
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### `discover` (client → server, UDP)
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```json
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{"type":"discover","protocol":"commonwealth-online","version":1}
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```
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### `discoverResponse` (server → client, UDP)
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```json
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{
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"type": "discoverResponse",
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"protocol": "commonwealth-online",
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"version": 1,
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"name": "Commonwealth Online Server",
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"port": 7777,
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"players": 2,
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"maxPlayers": 16
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}
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```
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Clients should connect to the **source IP** of the UDP response using the
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`port` from the response body.
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If UDP discovery is unavailable, the plugin may fall back to probing
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`127.0.0.1:7777` and the local LAN IPv4 address with a short TCP connect and
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`welcome` handshake check.
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## Main Rule
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The protocol should be testable outside Fallout 4 before it is used inside the F4SE plugin.
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`transform` packets carry position, movement state, optional `equippedItems`
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apparel snapshots, and optional `appearance` snapshots for best-effort proxy
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body/face visuals. The canonical field list and compatibility rules live in
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[`protocol/packets.md`](../protocol/packets.md).
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